Radon and Lung Cancer
What is radon and why is it important?
Radon is a gas, which obviously sounds
fairly innocent, however, it’s radioactive and can cause significant biological
damage if chronic exposure occurs. Radon is also a
member of the so called ‘noble’ gasses which simply means that under standard
conditions it has very low chemical reactivity. The problem is that this isn’t
relevant with regards to its radioactivity. The main health effect associated
with radon exposure is an increased risk of lung cancer. Radon’s life story
goes something like this… In the beginning, there was uranium. Uranium is
present in small amounts in most rocks and soils and over time undergoes
radioactive decay. This happens because the atomic nucleus of a uranium atom is
unstable and gives off radiation (including alpha, beta and gamma) over time.
As this happens, the uranium atom will lose, in the case of alpha decay, two
protons, and form an atom of thorium. Thorium is the first daughter product of
uranium. As this process continues, one of the other daughter products is radon
gas and because radon is a gas it can escape out of the ground through small
cracks and holes. Most of this radon gas can escape out into the atmosphere
and, ultimately, do us all very little harm. However, it can get into our homes
and accumulate. This accumulation can rapidly increase one’s exposure. Granite, in particular, can have very high concentrations of uranium and therefore homes built either on, or with, granite can have very high radon levels.
How does radon cause lung cancer?
When a single atom of radon enters one’s
lungs, normally, it is breathed straight back out again. Unfortunately, some do
remain inside the lungs and decay into the next daughter product. This is
called polonium-218. Now, as this decay occurs, an alpha particle is emitted
and heads straight towards the cells in either your lungs or your airways. You
may be thinking that this is just a mere alpha particle and that it’s not as
damaging as the gamma rays that you hear about all of the time. This is not
true. Gamma rays have a far greater penetrating power, but a far lower energy
compared to alpha particles. Normally alpha particles can be stopped by a thin
piece of material, such as a paper. However, such protection is not available
inside your lungs. The vast majority of the biological damage from radon is
attributable to the alpha particles directly damaging the DNA in your lung
cells. Those that are particularly keen may also realize that another isotope
of polonium is one of the main carcinogens in tobacco smoke.
Now that our radon atom has decayed into
polonium, it is no longer a gas. This provides a far greater problem.
Especially as after just a few minutes a number of rapid decays occur releasing
more and more radiation until what was once a humble radon atom is now lead.
One now has a nice atom of poisonous lead in one’s lungs!
But, before one gets too scared, the main
way in which radon causes lung cancer is through a multiplicative affect with
tobacco smoke exposure. This is known as a synergistic effect, where radon AND
tobacco smoke exposure cause more damage together than would be expected if
either were on their own. Many people who live in high radon homes and offices
their whole lives will be absolutely fine…probably.
What can I do to lower my risk?
Check the radon level in your home. If it’s
above the recommended level for your area then either: move; fit a radon sump; or open
the windows. But above all, don’t smoke.